17 6 Sir T. S. Raffles' s account 
enable the animal to browse upon the algae and other 
submarine vegetables. To facilitate this still farther, 
the anterior part of the jaw is bent downwards at an 
angle, in such a manner as to bring the mouth into 
nearly a vertical direction. There are no canine teeth. 
The molares are twelve in number, six in each jaw, 
placed far back on the horizontal part. They are 
cylindrical, with flat crowns ; the first are somewhat 
oblique, and worn to a kind of point ; the second are 
perfectly flat,* but the last are composed of two 
parallel and adhering cylinders. They are short, 
and scarcely project from the gums. The tongue is 
small and short. The nostrils are situated on the 
summit of the upper jaw, where it makes its curva- 
ture downwards. They penetrate obliquely, in such 
a manner that the upper semilunar edge pressing 
upon the lower surface, forms a perfect valve. The 
eyes are small, and situated on the sides of the cra- 
nium. The aperture of the ears is so small as with 
difficulty to be perceived, and is situated at some dis- 
tance behind the eyes. 
Body rounded, diminishing to the tail, and without any 
vestige of dorsal or ventral fins. The place of the 
anterior extremities is supplied by fins, which offer no 
appearance of nails, but are somewhat verrucose on 
their anterior margin. They are thick and fleshy, 
and neither from their form nor size capable of sup- 
porting or assisting the animal out of the water. 
Tail broad, horizontal, and of a crescent or semilunar 
form. 
